What factor determines and how equivalent operating hours and equivalent start is counted/calculated for gas turbine and steam turbine operation?

 

Gas Turbine

Equivalent number of starts formula
Equivalent number of starts ( De) = number of normal starts + 3 times number of fast starts + 10 tims number of no load disconnections

Equivalent number of hours formula
He = ka x HBA + KB + HBB + 3KA HPA + 3KB HPB
oR
He = total gas flame hours x fuel factor
He: Equivalent number of hours
KA: fuel oil factor A
Kb: fuel oil factor B
HBA: Base flame hours using fuel oil A
HBB: Base flame hours using fuel oil B
HPA : Peak flame hours using fuel oil A
HPB: : Peak flame hours using fuel oil B
Fuel factor:
Natural gas : 1
Distilled fuel oil : 1-1.5
Heavy distilled fuel oil : 1.5 – 2
1 peak hour = 3 He
1 fast start = 3 De
1 disconnection = 10 De

 

is it applicable to any gt?

CSA- i would like to have your comment, please

 

sandy,

I would say the formula is probably roughly applicable to any GT, but that to be most accurate for a specific GT you should consult the manufacturer of that specific GT for it's criteria and formula. Every manufacturer views equivalent operating hours slightly differently based on combustor design and hot gas path component design, so it would seem likely that there is no "one-size-fits-all" formula or parameter value determination.

 

Dear Sandy,

Mohamad did a very nice job of presenting some factors for calculating equivalent hours of operation. But I don't know what type of machine these numbers are referring to and I don't think you can generalize or assume that these are a applicable to a specific unit.

Each manufacturer should have their own set of variables to calculate equivalent operating hours based typically on number of starts, type of starts, type of fuel being burned, number of trips from part load or full load etc.

Some manufacturers have some very specific numbers, and some not so specific. So I thank Mohamad for providing the information that he did. But I think if you are looking for specific numbers that are applicable to your machine, you need to find documentation from the OEM that spells out how they specifically calculate equivalent operating hours.

I hope that CSA will back me up on this one.

 

I'm sorry. The correct (EMEND) formula is:
He=(Ka x HBA) + (Kb x HBB) + (3Ka x HPA) + (3Kb x HPB)

 

yes, this approach in estimating the maintenance interval is differ from one OEM to another. I reviewed the formula for our Siemens GTs and the older Westinghouse units and they are differ than the formula in this post.

GE doesn’t use this approach in determining maint interval. they base their calculation on hours and starts whichever reached first the unit have to be inspected.

 

Thanks everyone for your comment and input.

i love this forum and it is very interesting as well as helpful

thanks control.com

 

when we increment ES&EOH counters? Do we calculate once m/c reaches baseload? what about part load? not sure and want to clear my concept so please advise.

thx,
GTT